Design Considerations

To develop ActiveSync for your application, you first analyze the data to be synchronized. Define the object, the object type, the folder, the object identifier, and the database to hold the objects. Decide on the way to compare objects and the method for indicating that an object has changed. As you do this, keep the following requirements in mind:

• The object definition depends entirely on your application. It could be an appointment, an address, or some other item. The object type and the folder depend upon the object.
• The object identifier must satisfy several criteria. It cannot change once it is created; it cannot be reused for any other object; and it must be ordered. This allows object identifiers to be compared. Globally unique identifiers (GUIDs), for example, would satisfy these criteria.
• The database must accommodate the objects to be synchronized, but it can be a flat file, a Windows CE database, or some other custom format.
• Time stamps and version numbers are common ways to indicate that an object has changed.

Once these requirements are met, you can design and implement ActiveSync.